"We've been at this for 20 years! It hasn't always been easy, but looking at all of you here tonight, I can safely say we'll be doing it for another 20!"

It really isn't a question anymore: Slipknot are the most important metal band of the 21st century. They've shredded the metal rulebook in a way no other act have, they have an unprecedented run of great albums and they've never sold out or changed to suit the mainstream. Now, they've finally brought their travelling festival to Canada. As the armies of diehard fans (maggots, as they call themselves) fought their way through the CNE to reach the Budweiser Stage, the night was set to explode.

It seems Behemoth don't fare well in bright sunlight. Dealing with an unholy start time of 5:30 p.m., just minutes after many attendees get out of work, they soldiered on with their set. Adam "Nergal" Darski could be seen visibly sweating through his corpsepaint, and the crowd, though enthusiastic, was still mostly filing in. Their black metal assault was still powerful, and the double knockout of "Ora Pro Nobis Lucifer" and "Bartzebel" raised the loudest cheers.

By contrast, Gojira walked out to a wall of light so blinding it physically hurt to look at them. The brain-bending Frenchmen struck a special chord with the audience, bringing smoke machines and a breathtaking lightshow to go with their progressive metal set. Frontman Joe Duplantier kicked a smokestack into the crowd during the aptly named "Heaviest Matter in the Universe," dousing them with dry ice and getting a huge response in return. His brother Mario, behind the drum kit, must have used two dozen sets of sticks, throwing them into the crowd like candy multiple times during every song. Gojira won most technically accomplished band of the night, with massive closer "The Gift of Guilt" played almost exclusively with finger-tapping. Shoutout to the genius who brought the inflatable whale to send soaring over the crowd during Gojira's signature "Flying Whales." Brilliant.

Looking like a bunch of Peaky Blinders in their newsboy caps, Volbeat are here for one thing: to have fun. It takes guts to play Johnny Cash's "Ring of Fire" on an acoustic guitar to thousands of bloodthirsty metalheads, but Volbeat managed to make it look easy. Perfectly matched with the vibe of the CNE behind them, the rockabilly Danes brought out hometown hero Danko Jones for their rendition of mega-hit "Black Rose." The combination of "Slaytan" and "Dead But Rising" (interestingly, from different albums, though they blend so well it's hard to tell) went down like a dream and Volbeat looked like they were having the time of their life. Michael Poulson has a formidable set of lungs, showcased on "Black Rose" and brand-new track "The Everlasting." Volbeat still haven't fully connected with the North American scene the way they have with Europe, but there's no doubt they made a few new fans tonight.

As the sun sank, Slipknot rose. Tonight was all about the legacy, and what better way to remind everyone who they were dealing with than to bust out two of the band's heaviest early tracks, "People = Shit" and the timeless "(sic)." After ensuring that the entire audience would be eating out of the palm of his hand all night, Corey Taylor then really goes to town. Hit after hit after hit, until they can't possibly continue, Slipknot packed the perfect setlist for this only Canadian date of their current tour.

The band looked fantastic in their new white outfits (even if Corey Taylor's white trenchcoat can be mistaken for a bathrobe when not seen properly). MVP Award went to the new member, the yet-unidentified percussionist "Tortilla Man," who crawled Smeagol-like around the stage, bringing out the kind of energy a band of Slipknot's age should have left behind long ago. He seemed younger, clearly a longtime fan. Turntablist Sid Wilson (dressed like a mix between a Sith lord and Yolandi Vi$$er) mimed stabbing Tortilla Man to death halfway through the set. This was shortly before Clown started beating a beer keg with a flaming baseball bat. Just a typical night out with the 'Knot then?

There are so many big songs it's almost impossible to pick highlights. Most bands spend their entire careers trying to write something as iconic as "The Heretic Anthem." But to drop "Psychosocial," "The Devil In I," "Before I Forget" and new classic "Solway Firth" in sequence was just unfair. Leave some hits for the rest of the scene, guys! Slipknot know when to dive into the vault though, and rarity "Prothestics" made an eerie appearance before the classic, but rarely played, "Vermillion" sent the maggots into fits of nostalgia.

Slipknot are not a nostalgic band. Apart from their hiatus after the death of Paul Gray in 2009, they've never slowed down for a moment. The range of ages in the fans tonight was all the proof that's needed. As the classic metal legends start retiring, Slipknot are poised to become the biggest act in the metal world.